I have a 94 lt-1 and when I frist hit the gas it stumbles before taking off. It seems like it only happens when the pedal is first being pushed. Even while going down the highway if let off the gas and then mash back on the gas easy it stumbles then also. Plus my exhaust man.'s are getting cherry red under the heat sheilds. The car has loads of power and idle's great but I just can't seem to find out what is wrong. I just put new plugs in it after this started and it dosn't look to be running lean. Any help would be nice.

 

Stumble under initial acceleration usually means a plug wire or a spark plug breaking down because that is when the heaviest load is on the ignition system. Change plugs first, then if that doesn't fix it, opt for a set of good wires (A/C Delco). [8D]

 

Thanks for the info. I'll change the wires today since changing the plugs helped alittle.

 

Hey Mech,
What about his exhaust manifolds getting "cherry red"? You did not comment about this. You usually say something about the catalytic converter when exhaust manifolds get that hot. Just curious.

CG

 

Well the stainless manifolds will get red under normal driving conditions. Mine do, that is why they put those heat shields and plug wire guides on em. Not to say that the cat can cause that to, but if the car performs well under heavy acceleration, then probably can rule out cats.

 

So did the plugs/wires fix it? From what it sounds like its the great LT1 Opti, ive changed a handful of them on Fbody's there a pain in the ***. The tend to go bad for acouple reasons, 1 Miles, 2 Wetness like your waterpump going bad or you wash your engine bay alot.

 

Had to order the plug wires they should be here in the next day or 2. I'm also replacing the fuel filter and servicing the tranns why I have it parked. As far as the cats go the car runs great under load or athardtakeoff after it gets passed it stummble with ends around 1500rpms

 

Hope you are using good quality wires, not some cheap Autozone specials. [8D]

 

No they are not cheap wires. I am a strong believer in getting what you pay for. I know delco are good wires but I almost allways use MSD everthing when it's electrial that counts. They are 8mm wire's. I have had alot of good luck with MSD products in the past with hotrods that I have built.

Mech259,I wanted to get your thoughts on NGK plugs. That's the plugs I put in and they seem to be working pretty good. Also I had a little plastic pc on one of my vacum lines melted. It was located on the toppassenger sideof the engine. It hooked to hard plastic line's in to the intake and it kinda looked like some type of filter or reg. for the vacum lines. The hard vacumlines were running inside the wiring harness or atleast it looks that way. I am guessing they run to the insideof the car. When the car started to stumble this was one of the 1st things I found wrong but I don't know if it was that way when I bought the car or not. I have only had the car around 3 weeks or so.Thanks in advance if you have any idea.

 

NGK are ok plugs, not really my choice for domestic, but they should suffice. Are they platinum? Vacuum line breakage shouldn't cause the stumble you were speaking of. Sounds more like an ignition stumble. If plugs didn't fix your prob, I think you are on the right track with plug wires. When you get into changing them, you might find one that is chaffed and arcing to ground. Make sure and tie them off properly, because of the heat factor and LT's have been known to cross fire due to inductance on improperly routed plug wires. Good Luck. [8D]